1. Field of the Invention
The invention relates generally to the field of integrated circuit (IC) device packaging technology and, more particularly to thermal enhancement and electromagnetic interference (EMI) shielding in IC device packages.
2. Background Art
IC semiconductor dies are typically mounted in or on a package that is attached to a printed circuit board (PCB). Example IC device packages include ball grid array (BGA), pin grid array (PGA), and land grid array (LGA) packages. A conventional BGA package has an array of solder balls located on a bottom external surface of a package substrate. The solder balls are reflowed to attach the package to the PCB. The IC die is typically mounted to a top surface of the package substrate. Wire bonds typically couple signals of the IC die to the substrate. The substrate has internal routing that electrically couples the signals of the IC die to the solder balls on the bottom substrate surface. A molding compound encapsulates the IC die, wire bonds, and the entire or partial top surface of the substrate to provide environmental protection.
Die-up and die-down BGA package configurations exist. In die-up BGA packages, the IC die is mounted on the top surface of the substrate, so that the active surface of the IC die is directed away from the PCB. In die-down BGA packages, the IC die is mounted on the bottom surface of the substrate, so that the active surface of the IC die is directed towards the PCB.
Problems with conventional BGA packages include poor thermal performance and inadequate EMI protection. Resin substrates and plastic molding compounds have low thermal conductivity values (e.g., about 0.19-0.3 W/m.° C. for typical resin substrates, and about 0.2-0.9 W/m.° C. for typical molding compounds). When materials with poor thermal conductivity surround the IC die, heat generated by the IC die is trapped within the BGA package. Also, resin substrates and plastic molding compounds are transparent to EMI. Consequently, EMI generated by the IC die can pass through the resin substrate and plastic molding compound and interfere with electronic components outside of the package. Likewise, EMI generated by electronic components outside of the package can pass through the resin substrate and plastic molding compound and interfere with the IC die.
Therefore, what is needed is a die-up array IC device package that provides enhanced ability to dissipate heat generated by the IC die, and shields EMI emanating from the IC die, as well as EMI radiating toward the IC die from outside the package.